Medway School of Pharmacy, University of Kent, Chatham ME4 4TB, UK.
J Neural Transm (Vienna). 2012 Oct;119(10):1085-96. doi: 10.1007/s00702-012-0858-z. Epub 2012 Jul 14.
The natural rotation of the earth generates an environmental day-night cycle that repeats every 24 h. This daily transition from dawn to dusk provides one of the most important time cues to which the majority of organisms synchronise their activity. Under these conditions, natural light, a photic stimulus, provides the principal entraining cue. In mammals, an endogenous circadian pacemaker located within the suprachiasmatic nucleus (SCN) of the hypothalamus acts as a coordinating centre to align physiological activity with the environmental light-dark cycle. However, the SCN also receives regulatory input from a number of behavioural, non-photic, cues such as physical activity, social interactions and feeding routines. The unique ability of the SCN to integrate both photic and non-photic cues allows it to generate a rhythm that is tailored to the individual and entrained to the environment. Here, we review the key neurotransmitter systems involved in both photic and non-photic transmission to the SCN and their interactions that assist in generating an entrained output rhythm. We also consider the impact on health of a desynchronised circadian system with a focus on depressive affective disorders and current therapies aimed at manipulating the relationship between photic and non-photic SCN regulators.
地球的自然旋转产生了一个环境昼夜循环，每 24 小时重复一次。这种从黎明到黄昏的日常转变为大多数生物体提供了最重要的时间线索之一，使它们的活动与之同步。在这些条件下，自然光作为一种光刺激，提供了主要的同步线索。在哺乳动物中，位于下丘脑视交叉上核（SCN）内的内源性生物钟作为协调中心，使生理活动与环境的明暗循环保持一致。然而，SCN 还接收来自许多行为、非光的调节输入，如身体活动、社交互动和进食习惯。SCN 整合光和非光线索的独特能力使其能够产生一种适合个体并与环境同步的节律。在这里，我们回顾了参与 SCN 光和非光传递的关键神经递质系统及其相互作用，这些相互作用有助于产生同步的输出节律。我们还考虑了生物钟系统失同步对健康的影响，重点是抑郁性情感障碍和目前旨在操纵光和非光 SCN 调节剂之间关系的治疗方法。
